diff options
| author | Marek Szyprowski <m.szyprowski@samsung.com> | 2012-02-10 19:55:20 +0100 |
|---|---|---|
| committer | Marek Szyprowski <m.szyprowski@samsung.com> | 2012-05-21 15:06:13 +0200 |
| commit | a227fb92a0f5f0dd8282719386e9b3a29f0d16b2 (patch) | |
| tree | b990f647dcb38e17a4eef63b14f3358e6698e5c3 /arch/arm/mm | |
| parent | 553ac78877242b6d8b591323731df304140d0f99 (diff) | |
ARM: dma-mapping: remove offset parameter to prepare for generic dma_ops
This patch removes the need for the offset parameter in dma bounce
functions. This is required to let dma-mapping framework on ARM
architecture to use common, generic dma_map_ops based dma-mapping
helpers.
Background and more detailed explaination:
dma_*_range_* functions are available from the early days of the dma
mapping api. They are the correct way of doing a partial syncs on the
buffer (usually used by the network device drivers). This patch changes
only the internal implementation of the dma bounce functions to let
them tunnel through dma_map_ops structure. The driver api stays
unchanged, so driver are obliged to call dma_*_range_* functions to
keep code clean and easy to understand.
The only drawback from this patch is reduced detection of the dma api
abuse. Let us consider the following code:
dma_addr = dma_map_single(dev, ptr, 64, DMA_TO_DEVICE);
dma_sync_single_range_for_cpu(dev, dma_addr+16, 0, 32, DMA_TO_DEVICE);
Without the patch such code fails, because dma bounce code is unable
to find the bounce buffer for the given dma_address. After the patch
the above sync call will be equivalent to:
dma_sync_single_range_for_cpu(dev, dma_addr, 16, 32, DMA_TO_DEVICE);
which succeeds.
I don't consider this as a real problem, because DMA API abuse should be
caught by debug_dma_* function family. This patch lets us to simplify
the internal low-level implementation without chaning the driver visible
API.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Tested-By: Subash Patel <subash.ramaswamy@linaro.org>
Diffstat (limited to 'arch/arm/mm')
| -rw-r--r-- | arch/arm/mm/dma-mapping.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index e4ac5fc86b0a..a16993a5b7eb 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -660,7 +660,7 @@ void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int i; for_each_sg(sg, s, nents, i) { - if (!dmabounce_sync_for_cpu(dev, sg_dma_address(s), 0, + if (!dmabounce_sync_for_cpu(dev, sg_dma_address(s), sg_dma_len(s), dir)) continue; @@ -686,7 +686,7 @@ void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int i; for_each_sg(sg, s, nents, i) { - if (!dmabounce_sync_for_device(dev, sg_dma_address(s), 0, + if (!dmabounce_sync_for_device(dev, sg_dma_address(s), sg_dma_len(s), dir)) continue; |